(M548) That city then consisted of two parts—an inner and an outer city. The outer city was defended on two sides by the sea, and a sea wall. On the land side a long wall extended from the sea to the fortified high land of Achradina, so that the city could only be taken by a wall of circumvallation, so as to cut off supplies by land; at the same time it was blockaded by sea. But the delay of Nicias had enabled the Syracusans to construct a new wall, covering both the outer and inner city, and extending from the great port to the high land near the bay of Magnesi, so that any attack, except from a single point, was difficult, unless the wall of circumvallation was made much larger than was originally intended. Amid incredible difficulties the Athenians constructed their works, and in an assault from the cliff of Epipolæ, where they were intrenched, their general, Lamachus, was slain. But the Athenians had gained an advantage, and the siege was being successfully prosecuted. It was then that the Lacedæmonians arrived under Gylippus, who was unable to render succor. But Nicias, despising him, allowed him to land at Himera, from whence he marched across Sicily to Syracuse. A Corinthian fleet, under Gorgylus, arrived only just in time to prevent the city from capitulating, and Gylippus entered Syracuse unopposed. The inaction of Nicias, who could have prevented this, is unaccountable. But the arrival of Gylippus turned the scale, and he immediately prosecuted vigorous and aggressive measures. He surprised an Athenian fort, and began to construct a third counter-wall on the north side of the Athenian circle. The Athenians, now shut up within their lines, were obliged to accept battle, and were defeated, and even forced to seek shelter within their fortified lines. Under this discouragement, Nicias sent to Athens for another armament, and the Athenians responded to his call. But Sparta also resolved to send re-enforcements, and invade Attica besides. Sicilian forces also marched in aid of Syracuse. The result of all these gathering forces, in which the whole strength of Greece was employed, was the total defeat of the Athenian fleet in the Great Harbor, in spite of the powerful fleet which had sailed from Athens under Demosthenes. The Syracusans pursued their advantage by blocking up the harbor, and inclosing the whole Athenian fleet. The Athenians resolved then to force their way out, which led to another general engagement, in which the Athenians were totally defeated. Nicias once again attempted to force his way out, with the remainder of his defeated fleet, but the armament was too much discouraged to obey, and the Athenians sought to retreat by land. But all the roads were blockaded. The miserable army, nevertheless, began its hopeless march completely demoralized, and compelled to abandon the sick and wounded. The retreating army was harassed on every side, no progress could be made, and the